The Obama administration is set to announce approval of a 1,000-megawatt solar project on federal land in Southern California, the largest in a series of solar projects given the go-ahead in recent weeks.

The Interior Department has approved a permit for what will be the world’s biggest solar-power plant, on federal land in the desert near Blythe, Calif., 225 miles east of Los Angeles, according to Obama administration officials speaking on the condition of anonymity because the announcement had not been made.

The $6 billion project is being developed by Solar Millennium, a German solar developer. At peak output, the solar farm could generate enough clean electricity to power more than 300,000 homes, according to project developers.

Ms. O’Donnell said in Twitter and Facebook announcements Monday that she is “honored and humbled” to receive the endorsement of Mr. du Pont, who wrote a Wall Street Journal column last week pointing out the differences between her and her Democratic rival, New Castle County Executive Chris Coons.

While there was no formal event to announce the endorsement, Mr. du Pont said Monday that anyone who reads the Journal article can figure out who would win the Senate race if he had his way.

Mr. du Pont says he agrees with Ms. O’Donnell’s positions on most things, and that she has a chance of beating Mr. Coons, which would bring the Senate one vote closer to a GOP majority.

POSTAL SERVICE

Postmaster general to retire in December

John E. Potter, one of the nation’s longest-serving postmasters general, announced Monday that he will retire in December.

Patrick R. Donahoe, currently deputy postmaster general, was named to succeed him by the post office’s board of governors.

A New York City native, Mr. Potter, 55, has served in the Postal Service for 32 years and took over the top job at the agency in 2001.

Mr. Potter has served during a time that has seen the Postal Service struggle to deal with rising costs and declining mail volume as people switch over to the Internet.

The post office continues to face losses despite cuts in its spending and staff. It does not receive tax dollars for operations.

Currently, the agency is facing a $6 billion loss, and a request for a 2-cent increase in the price of a stamp was recently turned down by the independent Postal Regulatory Commission. The post office is appealing that decision.

ALASKA

Parties sue over write-in lists

ANCHORAGE | Alaska Democrats and Republicans finally agree on something: The state Division of Elections should not be providing voters with a list of write-in candidates at polling places.

The Alaska Democratic Party and the Republican Party of Alaska sued the Division of Elections on Monday, seeking a restraining order to immediately halt election workers from providing lists of write-in candidates to anyone who asks.

The matter is crucial this year as Sen. Lisa Murkowski, who was defeated by Joe Miller in the August GOP primary, mounts a write-in campaign for re-election.

Lawyer Thomas Daniel says state regulations are clear that information regarding a write-in candidate may not be “discussed, exhibited or provided” at the polling place.

TERRORISM

Biden says police needed in fight

ORLANDO | Vice President Joseph R. Biden Jr. is urging police and local law enforcement to share information and be on alert in the fight against terrorism, saying “it’s the local cop who’s going to discover the terrorist.”

Mr. Biden addressed the International Association of Chiefs of Police conference on Monday in Orlando. He said federal agencies need assistance from the local level to prevent terrorism.

Homeland Security Secretary Janet Napolitano echoed those thoughts. She says the FBI is operating under the premise that the individuals prepared to carry out terrorist acts are already in the country and may be unknown to the intelligence community and federal authorities.

ILLINOIS

Poll: Senate race remains neck and neck

CHICAGO | A new poll shows Republican Rep. Mark Steven Kirk and Democrat Alexi Giannoulias are about even as they head into their final week of campaigning for President Obama’s former Senate seat.

The Chicago Tribune/WGN poll released Sunday shows Mr. Kirk with a 44 percent to 41 percent advantage over Mr. Giannoulias. But that difference fell within the poll’s 3.7 percent margin of error.

A Tribune/WGN poll four weeks ago showed the candidates also about even. But that poll had Mr. Giannoulias leading with 38 percent of voters compared with Mr. Kirk’s 36 percent.

It found Mr. Kirk gaining ground among independents and suburban Chicago voters.

NEW YORK

Paladino wants $20B in services cut

ALBANY | Republican candidate for governor Carl Paladino says he wants to cut the Medicaid health care program for the poor in New York, while still providing service at the level of California.

Mr. Paladino promises to eliminate $20 billion from the nearly $52 billion program, which has grown with optional services approved by the Legislature. He said Monday that lawmakers have been serving the interests of the powerful health care lobby.

Democrat Andrew M. Cuomo also proposes an overhaul of Medicaid, focused on making the system more efficient. He would have the state take over its administration from counties and pool state and local pharmaceutical buying power to force lower prices.

Mr. Cuomo has no specific dollar target for savings like Mr. Paladino, but the Democrat proposes several ways to achieve savings.